The molecular process of crystallization from an oriented amorphous state was reproduced by molecular dynamics simulation for a realistic polyethylene model. The initial oriented amorphous state was obtained by uniaxi...
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The molecular process of crystallization from an oriented amorphous state was reproduced by molecular dynamics simulation for a realistic polyethylene model. The initial oriented amorphous state was obtained by uniaxially drawing an isotropic glassy state at 100 K. By the temperature jump from 100 K to 330 K, there occurred crystallization into the fiber structure, during the process of which we observed the developments of various order parameters. The real-space image and its Fourier transform revealed that a hexagonally ordered domain was initially formed, and then a highly ordered crystalline state with stacked lamellas developed after further adjustment of the relative heights of the chains along their axes.
The objectives of this study were to visually examine the surface and interior morphology of a new class of biodegradable hydrogels based on dextran-methacrylate and to quantify the porous structure of these hydrogels...
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Because stick-slip or other flow disturbances inside the die land have been suggested as a possible mechanism of the sharkskin, our effort was to observe any relevant periodic changes inside the die land during the sh...
Because stick-slip or other flow disturbances inside the die land have been suggested as a possible mechanism of the sharkskin, our effort was to observe any relevant periodic changes inside the die land during the sharkskin condition. We used particle tracking and time-resolved birefringence and two-dimensional light scattering in conjunction with a slit die attached to an extruder and a tubular glass die attached to a pressurized reservoir. Both dies could be observed up to the exit; both could also be directly observed downstream of the exit. While periodicities were easily seen in the slip-stick regime, none of the methods revealed any periodicity in the sharkskin regime. Direct observation of the sharkskin formation outside the die suggests a tearing and rolling mechanism as the origin of the sharkskin ridges found on polybutadiene extrudates.
Ionic aggregates in a series of Zn-neutralized poly(styrene- co -styrene sulfonate) (SPS) random ionomers have been imaged using scanning transmission electron microscopy. The Zn-rich aggregates were found to have two...
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The stacking sequence of several layers of self-assembled semiconducting CdSe nanoparticles has been investigated using transmission electron microscopy. FCC, HCP, saddle sites occupation and ring structures were foun...
The stacking sequence of several layers of self-assembled semiconducting CdSe nanoparticles has been investigated using transmission electron microscopy. FCC, HCP, saddle sites occupation and ring structures were found coexisting in the supercrystals formed by CdSe nanoparticles.
Novel gas permeation membranes were prepared from polysulfones and amine-modified polysulfones. The introduction of the primary amine moiety into polysulfone membranes led to an increase in permselectivity toward CO2 ...
Novel gas permeation membranes were prepared from polysulfones and amine-modified polysulfones. The introduction of the primary amine moiety into polysulfone membranes led to an increase in permselectivity toward CO2 in CO2/N2 separation and a significant increase in that toward O2 in O2/N2 separation.
This research studied the initiator efficiency for producing polymeric particles of poly(styrene-co-methyl methacrylate)copolymers by a Shirasu porous glass membrane(SPG)emulsification technique followed by suspension...
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This research studied the initiator efficiency for producing polymeric particles of poly(styrene-co-methyl methacrylate)copolymers by a Shirasu porous glass membrane(SPG)emulsification technique followed by suspension ***,ADVN,and AIBN were used as initiators and we found that BPO is the most suitable *** for various feed ratios of styrene/methyl methacrylate were thus synthesized by benzoyl peroxide,and their copolymer particle size,molecular weight distribution and pat-ride size distribution were *** n-BMA or 2-EHMA was added as the third monomer to decrease the terpolymer glass transition *** article describes the preparation technique,recipes and polymerization conditions for producing both copolymer and terpolymer particles,particle size changes,the corresponding particle morphologies and glass transition temperatures.
A polyhedral silsesquioxane (POSS)-methacrylate and poly(n-butyl acrylate) triblock copolymer (poly(MA-POSS)-b-BA-b-(MA-POSS)) prepared by atom transfer radical polymerization (ATRP) were synthesized and characterized...
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A polyhedral silsesquioxane (POSS)-methacrylate and poly(n-butyl acrylate) triblock copolymer (poly(MA-POSS)-b-BA-b-(MA-POSS)) prepared by atom transfer radical polymerization (ATRP) were synthesized and characterized. The molecular weight and composition of the triblock copolymer was determined from size exclusion chromatography and H NMR spectroscopy. The study aims to develop an understanding of the thermoplastic elastomeric properties as influenced by hard-block interactions and nanometer-scale organization in the materials.
The effect of crystalline morphology on the hydrolytic degradation behavior of poly(butylene succinate) (PBS) in an alkaline solution was investigated by using scanning electron microscopy, gel permeation chromatograp...
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